My DS's class used this. I can see how it could be a good way to teach for kids who have difficulty spelling and understanding meanings of words because the sorting does help them see the relationship of the various words with the same prefix, etc.
I did not care for it because much of the practice was simply rewriting the words and/or sorting them then "reflecting" on the sort. After you rewrote stuff or wrote the words in a few different ways, then you could do something interesting with them, like a comic, etc. We asked to modify the assignement which was fine with the teacher. Then, the next week they eliminated it from the curriculum.
I think it could be useful at the right level and my overal complaint with it was that my DS did not need to do the word study to know the words because he already knew them. He could give you the definition and he got 90-100 on spelling tests even though he did not do the word study.
On another note, this reflecting thing is a new concept that seems to be mixed up with common core as they are now having to do it with math as well. Again, I am not completely against it, but it should be leveled appropriately. Once my DS said, "I thought this problem was really easy because I already know all the math." I helped him better articulate that by asking a few questions, like what math - which he expanded on and told him he probably should drop the really.
